Compressed-gas circuit interrupters



June 19, 1962 G. J EASLEY ET AL 3,040,149

COMPRESSED-GAS CIRCUIT INTERRUPTERS Filed Dec. 30, 1960 7 S heets-Sheet 1 Fig.|.

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COMPRESSED-GAS CIRCUIT INTERRUPTERS Filed Dec. :50, 1960 7 Sheets-Sheet 4 7 Sheets-Sheet 5 1 6 M g lllllllllllllllllll f G. J. EASLEY ET AL COMPRESSED-GAS CIRCUIT INTERRUPTERS June 19, 1962 Filed Dec. 50, 1960 l l l O June 19, 1962 a. J. EASLEY ET AL 3,040,149

COMPRESSED-GAS CIRCUIT INTERRUPTERS Filed Dec. 50, 1960 '7 Sheets-Sheet 6 Fig.7.

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June 19, 1962 G. J. EASLEY ETAL 3,040,149

COMPRESSED-GAS CIRCUIT INTERRUPTERS Filed Dec. 30, 1960 7 Sheets-Sheet 7 Fig.9.

United States Patent ()filicc 3,040,149 Patented June 19, 1962 COMPRESSED-GAS CIRCUIT INTERRUPTERS Gilbert J. Easley. Edgewood, Richard E. Kane, Monroeville, and Jack E. Schrameck, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 30, 1960, Ser. No. 79,799 12 Claims. (Cl. 200-148) This invention relates to compressed-gas circuit interrupters in general, and, more particularly, to compressedgas circuit interrupters of the type involving an interrupting assembly comprising a main-current interrupting unit and an electrically-parallel impedance-current interrupting unit.

The general object of the present invention is to provide an improved compressed-gas interrupting assembly for a compressed-gas circuit interrupter in which fast opening and closing operations of the impedance interrupting unit is obtained to minimize the tendency to restrike on interrupting cable circuits.

A more specific object of the present invention is to provide an improved interrupting assembly, involving a main-current interrupting unit and an electrically-parallel impedance-current interrupting unit, in which valve means are associated with the impedance piston of the impedance interrupting unit to rapidly bring about opening operation of the impedance-current interrupting unit.

Another object of the present invention is to provide an improved compressed-gas circuit interrupter involving an interrupting assembly comprising a main-current interrupting unit and an electrically-parallel impedance-current interrupting unit in which the dumping means associated with the impedance-current interrupting unit is associated with the main exhaust valve for the interrupting assembly, and valve means are associated with the piston stern of the impedance interrupting unit to speed up the opening movement of the impedance interrupting unit.

Still a further object of the present invention is to provide an improved compressed-gas circuit interrupter of the type involving an interrupting assembly comprising a main-current interrupting unit and an electrically-parallel impedance-current interrupting unit in which an auxiliary dumping volume may be associated with the dumping means for the impedance-current interrupting unit to obtain snap-opening movement of the movable impedance contact.

Still a further object of the present invention is to provide an improved compressed-gas circuit interrupter involving an interrupting assembly comprising a main-current interrupting unit and an electrically-parallel impedance-current interrupting unit in which conduit means interconnects the dumping means for the impedance-current interrupting unit with the main exhaust valve, and, in addition, an auxiliary dumping volume is associated with the conduit means to effect extremely fast opening operation of the movable impedance contact.

In US. patent application filed June 7, 195 6, Serial No. 590,066, by Benjamin P. Baker, now Patent No. 2,965,- 735 issued December 20, 1960, entitled Compressed-Gas Circuit Interrupter and assigned to the assignee of the instant application, there is disclosed and described a compressed-gas circuit interrupter of radically novel construction. The tank structure employed is that of a conventional tank-type oil circuit interrupter, but instead of using oil, the interrupter, described in the foregoing patent application utilizes compressed air under pressure within the tank. The compressed air interrupting assemblies are supported from the lower interior ends of the terminal bushings, which extend into the tank structure in a manner similar to that of an oil circuit interrupter.

The compressed air circuit interrupter of the foregoing application included a pair of interrupting assemblies, bridged by a conducting cross-bar. Each interrupting assembly included a main-current interrupting unit and an electrically-parallel impedance-current interrupting unit. Generally, the operation was such that initial downward opening movement of the conducting cross-bar, or bridging member, connected to the breaker operating mechanism, initiated opening movement of a pair of main exhaust valves. Thus, a main exhaust valve was associated with each of the two interrupting assemblies.

The opening of the main exhaust valves quickly dumped the air on the rear side of the contact pistons secured to the movable main contact structures to cause the opening of the movable main contact structures and the consequent drawing of a pair of main current arcs in series. Following a predetermined opening travel of the main movable contact structures, slide valve means, associated with the movable main contacts, opened up a dumping or exhausting conduit means to the rear side of the impedance pistons, secured to, and movable with the movable impedance contacts of the two impedance interrupting units. By the time the pressure had dumped sufficiently on the rear sides of the movable impedance pistons, the main current arcs had been extinguished, and the interrupter current had been forced to pass through the two impedance-current interrupting units together with the seriallyrelated resistance means. The consequent delayed dumping action on the rear side of the impedance pistons insured that the main current arcs had been extinguished by a radial inward extending blast of gas through the main current-interrupting units and out through the hollow terminal studs associated with the terminal bushings supporting the two interrupting assemblies. The foregoing delayed action insured that the impedance-current interrupting units would open subsequent to the opening of the main-current interrupting units, and the radial inward extending blast of gas, past the movable impedance contacts, resulted in rapid extinction of the residual current arcs drawn at the impedance interrupting units.

Continued downward opening movement of the conducting bridging cross-bar effected disconnection at the two main exhause valves, permitting their reclosure, due to spring pressure, and the dumping conduits, consequently, refilled with pressurized air, and subsequent reclosing of the contact structure, both in the main-current interrupting unit and in the impedance-current interrupting unit transpired. The separation of the conducting bridging member from the main exhaust valves resulted in the interposition of two isolating gaps in the circuit to hold the voltage in the open-circuit position of the interrupter, since the contact structures in both interrupting assemblies reclose in the fully open position of the interrupter.

Capacitor switching tests on this type of breaker, such as described in the foregoing patent application, simulating switching of heavy underground cable circuits showed a tendency to restrike, which, in turn, caused insulation failure of the interrupter components. Time travel records of the impedance interrupter operation disclosed that this was due largely to a hesitation in the travel of the movable impedance contact, when the movable impedance contact was part-way open. This hesitation was caused by insufficient air exhaust on the under side of the impedance interrupter piston, which resulted in air-dashpot action. We have found that good contact speed, without hesitation, is required for restrike-free performance when switching capacitor circuits. It is, accordingly, a further object of the present invention to improve upon the dumping means associated with the impedance-current interrupting units to speed up the opening operation of the movable impedance contacts, and, thereby, render the circuit interrupter more adaptable for switching capacitor circuits and thus avoiding restriking at the contacts.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a vertical sectional view taken through one of the grounded tank structures of the compressed-gas circuit interrupter embodying features of the present invention, with the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a considerably enlarged vertical sectional view taken along the line IIII of the circuit interrupter of 'FIG. 1, illustrating one of the two serially related interrupting assemblies for the circuit interrupter, again the contact structure being illustrated in the closed circuit position;

FIG. 3 is a sectional view taken substantially along the line III-1H1 of FIG. 2, again the contact structure being illustrated in the closed-circuit position;

FIG. 4 is a top plan view of the interrupting asssembly of FIG. 2;

FIG. 5 is an inverted plan, or bottom view of the interrupting assembly of FIG. 2;

FIG. 6 is a considerably enlarged vertical section view taken through the main exhaust valve for the interrupting assembly of FIG. 2, the valve structure being illustrated in the closed position;

FIG. 7 is a fragmentary vertical sectional view taken through the dumping means associated with the impedance piston for the impedance current interrupting unit, illustrating the improved dumping means of the present invention, the impedance piston being shown in the closed contact position;

FIG. 8 is a modified type of improved dumping means for the impedance piston, which may be substituted for the improvement of FIG. 7, again the impedance piston being shown in the closed contact position;

FIG. 9 is a fragmentary vertical sectional view taken through a modified type of dumping arrangement for the impedance piston of the impedance interrupting unit, the impedance piston being illustrated in the contact closed position;

FIG. 10 is an inverted plan view of the modified dumping arrangement of FIG. 9, illustrating the general position of the several parts; and,

FIG. 11 is a detailed view of one of the component parts of the modified dumping arrangement of FIGS. 9 and 10.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a compressed-gas circuit interrupter. Generally, such a circuit interrupter '1 involves three pole-units for controlling the three phases of a transmission system. However, FIG. 1 illustrates a cross-sectional view taken through only one of such pole-units, say for example pole-unit A, pole-units B and C being omitted. As well known by those skilled in the art, and as set forth in the foregoing patent application, Serial No. 590,066, a common operating mechanism is provided for the three poleunits A, B and C. The common operating mechanisms, not shown, is effective to cause reciprocal horizontal movement of a horizontally extending opera-ting rod 2, which effects rotation of a crank-shaft 3, which, through a straight line motion mechanism 4, is effective to cause vertical reciprocal opening and closing movement of an insulating lift rod 5.

The insulating lift rod 5 has secured thereto, at the lower end thereof, a conducting bridging member, or cross arm 6, which serves to electrically interconnect a pair of serially related interrupting assemblies, generally designated by the reference numeral 7. As shown in FIG. 1, the interrupting assemblies 7 are maintained in a proper fixed position by adapter clamps 8, 9, which are threadedly secured to, and clamped with the threaded lower ends of tubular terminal studs 10, 11, extending axially through a pair of terminal bushings 12, 13; Line connections L l L are secured to the upper line terminals 14, 15 respectively of the terminal bushings 12, 13.

As illustrated in FIG. 1, the pair of serially related interrupting assemblies 7 are disposed within a grounded pressurized tank '16, which is supported upon a suitable base 1'7. As mentioned, the tank 16 contains compressed air under a relatively high pressure, say 250 p.s.i. Generally, as set forth in the aforesaid patent application, Serial No. 590,066, the interrupting blast of air emanating from the pressurized tank 16 interrupts the several arcs and passes through the hollow tubular terminal studs 11), 1, associated with the bushings 12, 13 to atmosphere through valve structures 18, 19 in a manner as indicated by the arrows 20. The valve structures 18, 19 serve to maintain a definite minimum pressure within exhaust chambers 21, 22, which i higher than atmospheric pressure, but which is considerably below that of the tank pressure 16.

As illustrated in FIG. 2, the exhaust tank structures 21,

22 are interconnected by passage means 23, so that normally the interior 24 is only slightly above atmospheric pressure, as communicated through the hollow tubular terminal stud-s r10, 11 of the bushings 12, 13.

FIG. 2, in addition, shows the interrupting assembly 7 as comprising a pair of electrically-parallel interrupting units 25, 26. The unit 25 is herein termed a main-current interrupting unit and is effective to draw a main current arc. The interrupting unit 26 is herein called an impedance current interrupting unit and is effective to interrupt the impedance arc, as more fully brought out hereinafter.

As shown in FIG. 2, the main-current interrupting unit 2 5 includes a movable main contact 27 cooperable with a relatively stationary main contact 28 to draw an are, not shown. An arcing horn 29 is provided, to which the upper terminal of the arc may attach during the opening operation. Encompassing the movable main contact 27 is a movable blast valve 30., which cooperates with a stationary blast valve seat 31.

A first operating means, generally designated by the reference numeral 3 2, is provided for operation of the main current interrupting unit 25. The first operating means 32 includes a first dumping means 36 effective to dump air on the lower side of a main current piston 34, which moves within a stationary operating cylinder 35. A compression spring 36 tends to maintain the movable blast valve 30 and the movable contact 27 in the closed position, as illustrated in FIG. 2. Additionally, a contact spring 37 biases the movable main contact 27 upwardly in a contact closed position relative to the movable main blast valve 30.

During the opening operation, means hereinafter more specifically set forth, are effective to dump the pressure within the region 38 below the movable main piston 34 l and to cause its consequent downward opening movement as a result of relatively high gas pressure within the region 39 acting downwardly upon the upper surface 40 of the main contact piston 34. The downward movement of the movable main piston 34 not only causes opening of the movable blast valve 30, and subsequent opening movement of the movable main contact 27, but, as will be apparent, the high pressure gas, within the region 39, passes radially inwardly toward the contact structure 27, 28 and into the exhaust chamber 21, as indicated by the arrows 4 1. This will effect rapid extinction of the main current are.

It will be observed that the movable main piston 34 has associated therewith a stem portion 42, which is suitably configura-ted to provide a slide valve 43. As a result, when the shoulder portion 44 of the slide valve 33 passes below a second conduit means 45, the low pressure within the region 38 is communicated through the exhausting pipe 46 to a second dumping means 48, associated with the movable impedance piston 49 constituting a part of the movable impedance interrupting unit 26.-

The first conduit means 50 interconnects the region 38, below the movable main piston 34, with a main exhaust valve, generally designated by the reference numeral 51, and illustrated more clearly in FIG. 6 of the drawings. As shown in FIG. 6, the main exhaust valve 51 includes an exhaust valve 52 biased upwardly to a closed position by a compression spring 53. The exhaust valve 52 controls the exhausting of gas upwardly through an exhaust tube 54, which communicates directly with the regions 23, 24, as shown more particularly in FIG. 2 of the drawings. Opening of the main exhaust valve 51 is brought about by a pin 55 (FIG. 3), movable with the outer extremity of the cross-bar 6, and hooking to a latch 56, the configuration of which is'more clearly shown in FIG. 6 of the drawings. Downward movement of the latch 56, as effected by downward opening movement of the conducting cross-bar 6, efiects opening of the exhaust valve 52 and consequent dumping of the region 38 below movable main contact piston 34 by way of the first conduit means 50.

It will be apparent, upon an examination of FIG. 6, that continued downward opening movement of the connecting cross bar 6 will cause the portion 57 of the pivotally mounted latch 56 to strike against a stop 58, halting the same and effecting counterclockwise releasing rotation of the latch 56 from the cross bar 6, thereby permitting reclosure of the main exhaust valve 51 due to the spring pressure 53.

As pointed out hereinbefore, the opening of the movable main contact structure 27, 28 is accompanied by the slide valve action 43 of the piston stem 42, and consequent dumping of the region 59 below the movable impedance piston 49. This will effect opening of the movable impedance contact 61 subsequent to opening of the movable main contact 27, which is desirable. In addition, the movable impedance piston 49 will effect opening of a movable blast valve 62 downwardly away from its cooperating stationary blast valve seat 63 and permit thereby a radial inward blast of gas to take place through the orifice opening 64 and into the exhausted region 24. This will interrupt the residual current arc, which is relatively small and of a relatively high power factor due to the presence of the resistance 65, which is in series circuit at this time.

In general, the foregoing construction and operation is similar to that set forth in the aforesaid Baker patent application, Serial No. 590,066. The improvement of the present invention relates specifically to the dumping arrangement illustrated more specifically in FIG, 7 of the drawings.

With reference to FIG. 7, it will be observed that the movable impedance piston 49 moves within an operating cylinder 65, and has a piston stem portion 66 movable therewith. The piston stem portion 66, is provided with a slide valve 67, which permits communication between the region 68, below the impedance piston 49, and a third conduit means 69, which leads directly to the main exhaust valve 51 (FIG. 6). More specifically, the exhaust pipe 46, which may, for example, be one half inch, leads to the sequencing slide valve 43 under the main interrupter, as was employed before in the aforesaid patent application, but according to the present invention, the exhaust pipe 46 is augmented by another more effective exhaust path, namely the third conduit means 69. The piston stem 66, on the under side of the movable impedance interrupter piston 49, is now grooved, as at 66a, to act as a slide valve, after a movement of one-eighth inch, to exhaust the air from the region 68 below the piston 49 into the pipe 69, which may be, for example, one inch in diameter. This one inch pipe 69 is directly connected to the main exhaust valve 51.

The new exhaust path is especially effective because it is pre-exhausted at the same time as the main interrupter. In other words, there is no high pressure air 6 in the one-inch pipe 69 to be exhausted at the same time as the air under the impedance interrupter piston 49. It may now be said that the new valve 67 and the one-inch pipe 69 constitute the main exhaust for the resistor interrupter 26, while the original valve 43 (stern of the main interrupter piston 34) and the one-half inch pipe 46 comprise now the pilot exhaust for the impedance unit 26 for proper sequencing.

The new arrangement, as illustrated in FIG. 7 in detail, shows a considerable improvement in operating speed of the resistor interrupter 26. Where the original arrangement, such as set forth in patent application Serial No. 590,066, required 1.5 cycles for total travel with a hesitation after one-half cycle, the new arrangement, such as set forth in FIG. 7, attains full travel in only 0.6 cycle with no hesitation. Subsequent capacitor switching tests showed a great improvement in elimination of restrikes.

Not only does the valve 66a, associated with the piston stem 66 of the impedance interrupter 26, result in extremely fast opening operation of the movable impedance contact 61, but also the improvement incorporates the function of fast reclosing, without waiting for the sequencing slide valve 43, under the main interrupter 25, to operate. Since the one-inch exhaust pipe 69 is connected directly to the main exhaust valve 51, high pressure air will be admitted through this pipe when the main exhaust valve 51 closes to reclose the impedance interrupter 26, without waiting for the slide valve 43, under the main interrupter piston 34, to pressurize the one-half inch exhaust pipe 46. Thus, the improvement of the present invention combines the two functions of high speed opening and high speed reclosing of the impedance interrupter 26.

FIGS. 9-1l illustrate a modified type of second dump ing means 71 for the impedance interrupter piston 49. The modified dumping arrangement 71, such as illustrated in FIG. 9 increases the speed of the impedance interrupter piston 49 in the following manner: A Y-shaped auxiliary dumping reservoir 72 is employed together with a snap action valve 73. When the onehalf inch exhaust pipe 46 is exhausted by the slide valve 43 under the main interrupter piston 34, the auxiliary dumping reservoir 72 is also exhausted through passage 74, but passage 75 to the impedance interrupter piston 49 is temporarily blocked by piston valve 73. It will be noted that the piston valve 73 constitutes a delayedacting valve, and has a shoulder portion 77 and a piston surface 78. As soon as the pressure is reduced sufficient- 1y under the delayed piston valve 73, the pressure at passage 74 will cause the piston valve 73 to open. The snap action is obtained by tank pressure entering small holes 80 to apply pressure to the top side of shoulder 77 of delay valve 73 after the initial opening movement of valve 73.

Opening passage 75 allows the air within the region 59, under the impedance interrupter piston 49, to exhaust quickly into reservoir 72 and the one-half inch pipe 46, which have been pre-exhausted. If, for example, the volume of the reservoir 72 and the pipe 46 are equal to the volume 59 under the impedance interrupter piston 49, the pressure in the combined volumes will drop quickly to one-half the original pressure, thus permitting high operating speed of the impedance interrupter piston 49 and contact 61.

A modification of the second dumping means 48, as shown in FIG. 7, is illustrated in FIG. 8 of the drawings. The modified second dumping means 83 includes the addition of the reservoir 72a, similar to the reservoir 72 of FIGS. 9 and 10, to increase the volume of the preexhausted pipe 69. Thus, the volume of the one-inch pipe 69 would be increased by the addition of the auxiliary dumping reservoir 72a. If this were done, the use of a smaller sized pipe 69 would be permissible due to the extra volume of reservoir 72a.

From the foregoing description, it will be apparent that there has been provided improvements for speeding up the operation of the interrupter 26 to facilitate the final positive interruption of the residual current passing through the interrupter 1. There have been illustrated three modified arrangements for accelerating the movement of the movable impedance contact 61. The first arrangement, such as illustrated in FIG. 7, includes the additional exhaust pipe 69 together with the slide valve action 66d carried by the piston stem 66. The second modified dumping arrangement includes the snap acting valve 73, illustrated in FIG. 9, together with the auxiliary dumping volume 72. The third modified dumping arrangement, such as illustrated in FIG. 8, is similar to that of the first arrangement, illustrated in FIG, 7, but permits the use of a smaller sized pipe 69, because of the addition of an auxiliary dumping reservoir 72a to the exhaust pipe 69.

The use of any one of the three foregoing arrangements results in an accelerated opening action of the impedance contact 61, and also positive travel of the movable impedance contact 61 to avoid the possibility of restrikes during the interruption of capacitor circuits. It speeds up the opening operation of the breaker as a whole and thereby improves its overall performance.

Although there has been illustrated and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. A compressed gas circuit interrupter including means defining an enclosure containing a gas underpressure, an interrupting assembly disposed within said enclosure and including a main current interrupting unit and an impedance interrupting unit, means connecting said main current interrupting unit and said impedance interrupting unit in electrical parallel with each other, said main current interrupting unit having a movable main contact associated therewith, said impedance interrupting unit having a movable impedance contact associated therewith, a main exhaust valve, first operating means for the main current interrupting unit including a main current piston movable with the movable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to efiiect opening movement of said movable main contact to force the current to flow through the parallel disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for the impedance interrupting unit including an impedance piston movable With said movable impedance contact and also including second dumping means for exhausting the gas from the rear side of said impedance piston to effect thereby opening movement of said movable impedance contact, sequencing means including second conduit means interconnecting the first dumping means with said second dumping means for actuating said second operating means subsequent to the actuation of said first operating means to effect opening movement of the impedance contact only after the opening movement of said movable main contact, third conduit means interconnecting said second dumping means with said main exhaust valve, and valve means associated with said impedance piston to interconnect said main exhaust valve through said third conduit means with the rear side of said impedance piston only after a predetermined drop of pressure Within said second conduit means.

2. A compressed gas circuit interrupter including means defining an enclosure containing a gas under pressure, an interrupting assembly disposed within said enclosure and including a main current interrupting unit and an impedance interrupting unit, means connecting said main current interrupting unit and said, impedance interrupting unit in electrical parallel with each other, said main movable with the movable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to effect opening movement of said movable main contact to force the current to flow through the parallel disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for the impedance interrupting unit including an impedance piston movable with said movable impedance contact and also including second dumping means for exhaust-ing the gas from the rear side of said impedance piston to effect thereby opening movement of said movable impedance contact, sequencing means including second conduit means interconnecting the first dumping means with said second dumping means for actuating said second operating means subsequent to the actuation of said first operating means to effect opening movement of the impedance contact only after the opening movement of said movable main contact, third conduit means interconnecting said second dumping means with said main exhaust valve, a piston stem movable with said impedance piston, and a slide valve associated with said piston stem to interconnect said main exhaust valve through said third conduit means with the rear side of said impedance piston only after a predetermined drop of pressure within said second conduit means.

3. A compressed gas circuit interrupter including means defining an enclosure containing a gas under pressure,

an interrupting assembly disposed within said enclosure and including a main current interrupting unit and an impedance interrupting unit, means connecting said main current interrupting unit and said impedance interrupting unit in electrical parallel with each other, said main current interrupting unit having a movable main contact associated therewith, said impedance interrupting unit having a movable impedance contact associated therewith, a main exhaust valve, first operating means for the main current interrupting unit including a main current piston movable with themovable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to effect opening movement of said movable main contact to force the current to flow through the parallel-disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for the impedance interrupting unit including an impedance piston movable with said movable impedance contact and also including second dumping means for exhausting from the rear side of said impedance piston to efiect thereby opening movement of said movable impedance contact sequencing means including second conduit means interconnecting the first dumping means with said second dumping means for actuating said second operating means subsequent to the actuation of said first operating means to efiect opening movement of the impedance contact only after the opening movement of said movable main contact, third conduit means interconnecting said second dumping means with said main exhaust valve, valve means associated withsaid impedance piston to interconnect said main exhaust valve through said third conduit means with the rear side of said impedance piston only after a predetermined drop of pressure within said second conduit means, and an auxiliary dumping reservoir connected to said third conduit means to afford additional exhausting impulse to said impedance piston.

4. A compressed gas circuit interrupter including means defining an enclosure containing a gas under pressure, an interrupting assembly disposed Within said enclosure and including a main current interrupting unit and an impedance interrupting unit, means connecting said main current interrupting unit and said impedance interrupting unit in electrical parallel with each other, said main current interrupting unit having a movable main contact associated therewith, said impedance interrupting unit having a movable impedance contact associated therewith, a main exhaust valve, first operating means for the main current interrupting unit including a main current piston movable with the movable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to eifect opening movement of said movable main contact to force the current to flow through the parallel disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for the impedance interrupting unit including an impedance piston movable with said movable impedance contact and also including second dumping means for exhausting the gas from the rear side of said impedance piston to effect thereby opening movement of said movable impedance contact, sequencing means including second conduit means interconnecting the first dumping means with said second dumping means for actuating said second operating means subsequent to the actuation of said first operating means to eifect opening movement of the impedance contact only after the opening movement of said movable main contact, third conduit means interconnecting said second dumping means with said main exhaust valve, a piston stem movable with said impedance piston, a slide valve associated with said piston stem, to interconnect said main exhaust valve through said third conduit means with the rear side of said impedance piston only after a predetermined drop of pressure within said second conduit means, and an auxiliary dumping reservoir connected to said third conduit means to afford additional exhausting impulse to said impedance piston.

5. A compressed gas circuit interrupter including means defining an enclosure containing a gas under pressure, an interrupting assembly disposed within said enclosure and including a main current interrupting unit and an impedance interrupting unit, means connecting said main current interrupting unit and said impedance interrupting unit in electrical parallel with each other, said main current interrupting unit having a movable main contact associated therewith, said impedance interrupting unit having a movable impedance contact associated therewith, a main exhaust valve, first operating means for the main current interrupting unit including a main current piston movable with the movable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to effect opening movement of said movable rnain contact to force the current to flow through the parallel disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for the impedance interrupting unit including an impedance piston movable with said movable impedance contact and also including second dumping means for exhausting the gas from the rear side of said impedance piston to effect thereby opening movement of said movable impedance contact, sequencing means including second conduit means interconnecting the first dumping means with said second dumping means for actuating said second operating means subsequent to the actuation of said first operating means to effect opening movement of the impedance contact only after the opening movement of said movable main contact, said second dumping means including a dumping volume on the rear side of the impedance piston and an auxiliary dumping reservoir, a delay valve having a piston surface exposed to said auxiliary dumping reservoir, and said second conduit means being connected to said auxiliary dumping reservoir and also to said piston surface, whereby predetermined drop in pressure Within said second conduit means and auxiliary dumping reservoir will effect quick opening of said relay valve and thereby communication between said dumping volume and said auxiliary dumping reservoir.

6. A compressed gas circuit interrupter including means defining an enclosure containing a gas under pressure, an interrupting assembly disposed within said enclosure and including a main current interrupting unit and an impedance interrupting unit, means connecting said main current interrupting unit and said impedance interrupting unit in electrical parallel with each other, said main current interrupting unit having a movable main contact associated therewith, said impedance interrupting unit having a movable impedance contact associated therewith, a main exhaust valve, first operating means for the main current interrupting unit including a main current piston movable with the movable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to effect opening movement of said movable main contact to force the current to flow through the parallel disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for the impedance interrupting unit including an impedance piston movable with said movable impedance contact and also including second dumping means for exhausting the gas from the rear side of said impedance piston to effect thereby opening movement of said movable impedance contact, sequencing means including second conduit means interconnecting the first dumping means with said second dumping means for actuating said second operating means sub sequent to the actuation of said first operating means to efiect opening movement of the impedance contact only after the openingtmovement of said movable main contact, said second dumping means including a dumping volume on the rear side of the impedance piston and an auxiliary dumping reservoir, a delay valve having a piston surface exposed to said auxiliary dumping reservoir, said delay valve having a shoulder portion, port means communicating pressure within said enclosure to said shoulder means following predetermined opening movement of said delay valve for snap-opening movement of the delay valve, and said second conduit means being connected to said auxiliary dumping reservoir and also to said piston surface, whereby predetermined drop in pressure within said second conduit means and auxiliary dumping reservoir will effect quick opening of said delay valve and thereby communication between said dumping volume and said auxiliary dumping reservoir.

7. A compressed gas circuit interrupter including tank means containing a gas under pressure, a pair of interrupting assemblies disposed within said tank means, each interrupting assembly including a main current interrupting and an impedance interrupting unit, a conduct ing cross-bar electrically bridging the two interrupting assemblies means connecting the main current interrupting unit and the impedance interrupting unit for each assembly in electrical parallel, the main current interrupting unit having a movable main contact associated therewith, the impedance interrupting unit having a movable impedance contact associated therewith, a main exhaust valve for each interrupting assembly, said conducting cross-bar initiating opening of the two main exhaust valves associated with the two interrupting assemblies during the initial portion of the opening operation, first operating means for the main current interrupting unit of each interrupting assembly including a main current piston movable with the movable main contact and also including first dumping means for exhausting the gas from the rear side of said piston to eifect opening movement of said movable main contact to force the current to flow through the parallel disposed impedance interrupting unit, first conduit means interconnecting said main exhaust valve with said first dumping means, second operating means for each interrupting assembly for actuating the impedance interrupting unit including an impedance piston movable with said movable impedance contact and also including second dumping means for exhausting thev gas from the rear side of said impedance piston to thereby effect opening movement of said movable impedance contact, sequencing means for each interrupting assembly including second conduit means in terconnecting the first dumping means with said second dumping means for actuating said second operating means for each interrupting assembly subsequent to the actuation of the first operating means for the respective interrupting assembly to effect thereby opening movement of the impedance contact only after the opening movement of said movable main contact, third conduit means interconnecting said second dumping means with said main exhaust valve for each interrupting assembly, and valve means associated with the impedance piston for each ininterrupting assembly to interconnect said main exhaust valve through said third conduit means for the respective interrupting assembly with the rear side of the impedance piston only after a predetermined drop of pressure within said second conduit means.

8. The compressed gas circuit interrupter according to claim 7, wherein the impedance piston for each interrupting asembly has a piston stem movable therewith, and a slide valve is associated with the piston stem.

9. The compressed gas circuit interrupter according to claim 7, wherein an auxiliary dumping reservoir is connected to the third conduit means for each interrupting assembly to afford additional exhausting impulse to the impedance piston for the particular interrupting assembly.

10. The compressed gas circuit interrupter according to claim 8, wherein an auxiliary dumping reservoir is connected to the third conduit means for each interrupting assembly to afford additional exhausting impulse to the impedance means for the particular interrupting assembly.

11. A compressed gas circuit interrupter including the tank containing a gas under pressure, a pair of interrupting assemblies disposed Within said tank, each interrupting assembly including a main current interrupting unit and an impedance interrupting unit, a conducting cross-bar electrically interconnecting the two interrupting assemblies within the tank, means connecting said main current interrupting unit and said impedance interrupting unit for each interrupting assembly in electrical parallel with each other, the main current interrupting unit of each interrupting assembly having a movable main contact associated therewith, the impedance interrupting unit for each interrupting assembly having a movable impedance contact associated therewith, a main exhaust valve for each interrupting assembly, saidconducting cross-bar initiating opening movement of the two main exhaust valves for each interrupter at the beginning of the opening oprespectively assembly, second operating means for the impedance interrupting unit for the particular interrupting assembly including an impedance piston movable with said movable impedance contact and also including second dumping means for exhausting the gas from the rear side of said impedance piston to effect thereby opening movement of said movable impedance contact, sequencing means including second conduit means for each interrupting assembly interconnecting the first dumping means with said second dumping means for the respective interrupting assembly for actuating said second operating means for the particular interrupting assembly subsequent to the actuation of said first operating means to efiect opening movement of the impedance contact only after the opening movement of said movable main contact, the second dumping means for each interrupting assembly including a dumping volume on the rear side of the respective impedance piston and an auxiliary dumping reservoir, a delay valve for each interrupting assembly having a piston surface exposed to said auxiliary dumping reservoir, and said second conduit means being connected to said auxiliary dumping reservoir and also to said piston surface, whereby predetermined drop in pressure within said second conduit means for each interrupting assembly and the auxiliary dumping 'reservoir for the respective interrupting assembly will effect quick opening of said delay valve of each interrupting assembly and thereby communication between said dumping volume and the auxiliary dumping reservoir for the particular interrupting assembly.

12. The compressed gas circuit interrupter according to claim 11, wherein the delay valve for each interrupting assembly has a shoulder portion, andrport means com,- municating pressure within said tank to said shoulder means following predetermined opening movement of said delay valve for snap opening movement of the delay valve for the particular interrupting assembly.

References Cited in the file of this patent UNITED STATES PATENTS 2,965,735 Baker Dec. 20, 1960 

